Easy trap to tame an argy!

Make four wooden gate frames and two gates. Place them, one in front of the other and make sure the gaps between them aren't big enough for the argy to escape. Put a gate on the first and last doorframe. Close the last door and leave the entrance open. Aggro the argy and lead it in the trap, once its inside close the gate. You can exit the trap from the gaps between the gate frames.

Then you can just knock it out!

Warning: don't leave the argentavis in the trap for too long without knocking it out because it can break wood

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